From the German "Offenlegungsschrift" No. 2 339 048, a safety device is known where an air pillow or cushion is inflated in the event of an accident or crash of low impact force by a single gas generator. However, in the event of a serious accident, the air pillow or cushion is inflated by a plurality of simultaneously fired gas generators in a sudden burst. The purpose of this approach is to avoid subjecting passengers to very rapidly inflating cushions when a crash or accident of minor consequence occurs.
From the German "Offenlegungsschrift" No. 2 224 201, it is also known to inflate the air cushion or pillow intermittently. In such an arrangement, fuel chambers disposed in a generator housing and containing at least two propellant charges have respective gas discharge outlets communicating with the air cushion or pillow. Propellant charges of the individual fuel chambers are fired successively and prior to the propellant cut-off of the respective fuel chamber supplying gas to the air pillow or cushion. The total quantity of the gas expelled from the generator corresponds to the required quantity for filling the air cushion. It has been ascertained that during such intermittent inflations of the air cushion, the latter is securely protected from any excessive mechanical and thermal loads. Further, the sounds accompanying the inflation process in the interior of the vehicle can be significantly reduced. By this approach, secondary injuries or damage to the passengers of the vehicle can be avoided, such as injuries to the ear drum.